数字频率计设计.doc

数字频率计设计 摘要：本文提出设计数字频率计的多种方案，重点介绍以单片机AT89C52为控制核心，实现频率测量的数字频率计设计。 测频的基本原理是采用在高频段直接测频法，在低频段测周期法的设计思路；硬件部分由放大电路、波形变换和整形电路、闸门时基控制电路、分频电路、单片机和数据显示电路组成；软件部分由信号频率测量模块、周期测量模块、定时器中断服务模块、数据显示模块等功能模块实现。应用单片机的控制功能和数学运算能力，实现计数功能和频率、周期的换算。设计的频率计测量范围能够达到2HZ～50MHZ，满足所要求的频率范围，测量精度较高，平均相对误差仅为0.3401%。另外，文章对频率测量过程中数据误差的来源进行了探讨，提出了减小误差的措施。最后，文章还对频率计的设计方案提出了可扩展的地方。 关键词：数字频率计；单片机AT89C52；频率测量；周期测量；误差 The design of digital frequency meter LU Jiabin College of Engineering and Technology, Southwest University, Chongqing 400716, China Abstract：This article proposes many kinds of plans design frequency meter, highlighting the design taking monolithic integrated circuit AT89C52 as the control core, the realization frequency measurement of digital frequency meter. Selected design ideas which directly measuring frequency law in the high-band and testing cycle law in the low-band; The hardware partially is composed by enlarged circuit、the profile transformation and the reshaping circuit、the gate at the base control circuits、sub-frequency circuits、the microcontroller and the data display electric circuit; The software design is achieved by many functional modules, such as the signal frequency measurement module、the signal cycle survey module、timer interruption of service module、the data display module and so on. Achieving counting function and conversion between cycle and frequency by using control functions and mathematics operation ability of microcontroller. Like these the survey scope can achieve 2HZ ~ 50MHZ, both can reach the frequency range requirements designed, the measuring accuracy high, and can cause the average relative measuring error to be only 0.3401%. In addition, the article has carried on the discussion to the data error origin in the process surveyed the frequency, and proposed the measures reduce the measuring error. Finally, the article also raise the frequency of the design options will be further improved. Key Words：; Microcontroller AT89C52; Frequency measurements; Measure